Tin-containing dithiocarbamate compounds and lubricants containing them



I k N.-

TIN-CONTAINING DITHIOCARBAMATE (M- rov ns AND LUBRICANTS CONTAINING John P. McD'ermott, Springfield, N. J., assignor to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Application September 21, 1953, Serial No. 381,511

17 Claims. (Cl. 25233.6)

The present invention relates to a new class of tincontaining compounds and more particularly to the use of these compounds as additives for various hydrocarbon a more and more efiicient refining methods in order to improve their stability and reduce their tendency to form carbon and deposits of solid matter or sludge. While such highly refined materials possess many advantages, their resistance to oxidation, particularly under conditions of severe service, is generally decreased and they are more prone to form soluble acid oxidation products which are corrosive. They are generally less elfective than the untreated products in protecting the metal surfaces which they contact against rusting and corrosion due to oxygen and moisture. Such lubricants also often deposit thick films of varnish on hot metal surfaces, such as the pistons of internal combustion engines. I

In accordance with the present invention a new class of chemical compounds has been discovered, and these compounds have been found to reduce the tendency of refined lubricating oils and other hydrocarbon products to corrode metal surfaces when added in small quan tities to such materiai-s. These additives are active in reducing the corrosion of copper-lead and cadmiumsilver bearings which are employed in internal combustion engines, they are likewise effective in inhibiting the oxidation of hydrocarbon products generally and especially those of petroleum origin, andthey im'part othe'r useful properties to various products:

The new class of compounds forming the subject of the present invention are tetravalent tin compounds having four organo radicals comprising at least two oil solubilizing' hydrocarbonradicals attached directly to the tin through carbon atoms and having at'lea'st one thio-' carbarnate radical attacheddirectly'to the tin through a sulfur atom. The compounds are conveniently formed 1 by reactingan" organo-tetravalent tin halide with-a salt of a thiocarba'mic acid in such manner that' halogen in the tin compound is substantially completely replaced by the organic radical: 4 The compounds-are stable and soluble in-the usual'hydroc'arbon products such as fuels, lubricating oils and the like; are good 'anticorrosive' agents for organic materials that 'te'rid to corrode the usual metals, and have other useful'properties:

The new class of compounds ofthe'present'invention may be more accurately defined by thefollowing general formula:

I 2* R ..sn(--s-'d--N wherein R is a hydrocarbon-radical, wis 2 to 3, y is l to 2 and w plus y totals 4. R is also a hydrocarbon radical.

2,786,814 Patented Mar. 26, 1957 R and R each preferably have 1 to 20 carbon atoms and may be alkyl, alkenyl, cyclo-alky-l, aryl, aralkyl, and alkaryl radicals. Alkyl radicals such as methyl, iso-' propyl, octyl, dodecyl, octadecyl and other straight or branched chain radicals are preferred. Other radicals include .phenyl, naphthyl, benzyl, octylphenyl, ethylcyclohexyl, and the like. R and R should include sufiicicnt carbon atoms to render the compound soluble in hydrocarbon products and preferably a total of at least it) carbon atoms are contained in R and R.

The organo-tetravalent tin halides used in the reparation of the compounds of the present invention may Be represented by the following formula:

)wSn( wherein R is a hydrocarbon radical as defined above, X is a reactive halogen such as chlorine, bromine and iodine,- w is 2 to 3, y is 1 to 2 and w plus y totals 4. 1 Specific compounds include dibutyltindichloride, triphenyltini- 'odide, tri-tert.-octyltiniodide, tri cyclohexyltinchloride, di-n-hexyl-tindibromide and the like. The halide preferably has =two'R radicals, and the R radicals are preferably alkyl radicals. The organo-tetravalent halides may be prepared by means well known to the art.

' The salts of dithiocarbar'nic' acids may be represented by the following formula:

NiisY R/ Dithiocai'bamate R has the meaning defined above. Y is a cation and is preferably a metal equivalent of hydrogen. The reactive :alkali and alkaline earth metals such as sodium, potassium, calcium and the like may be used. Ammonium or amine salts may also be used. The dithiocarbamates are prepared by well-known means. v

Specific salts of the above general types include potassium, sodium, lithium, barium, ammonium and the like salts of isopropyl ethyl dithiocarbamic acid, didodecyl dithioca-rbamic acid, diethyl dithiocarbamic acid, di phenylethyl dithiocarbamic acid, di-(methylcyclohexyl) dithiocarbamic acid, 7 di- (2-ethylhexyl) dithiocarbamic acid, dice'tyldithiocarbamic acid, di-Lorol-B ditliiocarbamic acid (where Lorol B compounds ,are derived from Lorol-B alcohol which is a commercial mixture of higher alcohols commonly derived from coconut oil and having from 8 to 18 carbon atoms per molecule), and the like;

The particular compound selected .will depend largely on the concentrationsused and the specific properties to be improved in various hydrocarbon products. In .general, however, the thiocarbamate derivatives, in addition to having good antioxidant properties, are useful as additives for minimizing ring stickingin motors.

Suflicient salt of the acid is reacted with the tin halide compound to replace the halogen substantially completely. A typical reaction is represented by the following' formula:

Thus from 1 to 2 mols of the desired sulfur-containing plete reaction, In carrying out the're action, the sulfurcontaining salt may be added relatively slowly to the tin halide with care being taken to prevent excessive temperature rise as a result of the exothermic reaction which takes place. The reactants may be heated together for a period of from about 0.5 to 2 hours, depending on the types of materials present. Preferably, the reaction temperatures are maintained in a range of about 10 to 100 C. Conveniently, the reaction is carried out in the presence of an inert solvent in which the halide reaction by-products are insoluble or from which such by-products may be readily removed. Such solvents include petroleum ether, methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, dioxane and the like. The heating step may be carried out under refluxing conditions when a solvent is used. The resulting metal halide will generally precipitate out of solution and may be removed by filtration, decantation or by other means. Solvent may be removed from the finished product by stripping with nitrogen or other inert gas, by distillation or by other means. A desired method for producing a relatively pure product is to filter the material, preferably before solvent is removed, through a diatomaceous filter aid such as Hy-flo.

If the products of the present invention are added to a mineral oil for inhibiting oxidation and preventing corrosion of metal parts and the like, they are preferably used in proportions of about 0.01 to 5% or by weight based on the total composition. A preferred range is from about 0.1 to 2% by weight. Concentrations up to as high as or even higher may be used for extreme pressure lubricants, cutting oils, and the like. It is usually preferred, when marketing the additive commercially and especially when intended for use in lubricating oils, to prepare a concentrated lubricating oil solution in which the amount of additive in the composition ranges from about 20 to 50% or up to 75% by weight, depending on the solubility of the additive in the oil. The concentrate is then conveniently transported and stored in such form and may be subsequently blended with a base lubricant in the required amount before being used as a crank case oil or the like.

The invention will be more fully understood by reference to the following examples. It is pointed out, however, that the examples are given for the purpose of illustration only and are not to be construed as limiting the scope of the present invention in any way.

EXAMPLE I.PREPARATION OF PRODUCTS Product A.-Dilauryltindi(dibutyldithiocarbamate) Product B.-Dibutyltindi(diamyldithiocarbamate) This reaction was conducted by the procedure described in connection with Product A using 30.4 g. dibutyltindichloride (0.1 mol) and 51.0 g. sodium diamyldithiocarbamate (0.2 mol). A viscous liquid was obtained which analyzed 3.6% N, 17.0% S, and 9.0% Sn.

EXAMPLE II.LABO RATORY BEARING CORRO- SION TEST A blend was prepared containing 0.25 by weight of the products prepared as described in Example I using as the base oil a solvent extracted, paraffinic type mineral lubricating oil of S. A. E.-20 viscosity grade. Samples of these blends and a sample of the unblended base oil were submitted to a laboratory test designed to measure Bearing Corrosion Life (Hours to lose mg. per 25 sq. cm. of Cu- Pb bearing) Product in Base 011 (0.25 wt. percent active ingradient) The additives of the present invention may be used in various lubricating oil base stocks derived from petroleum distillates and residuals refined by conventional means. Hydrogenated oils or white oils may be employed as well as synthetic oils prepared by polymerization of olefins, by reaction of oxides of carbon with hydrogen or by hydrogenation of coal. The products may also be used in the synthetic 'polyether and polyester-type lubricantsand the like as such or blended with mineral lubricants. The lubricants will usually range from about 35 to seconds (Saybolt) viscosity at 210 F.

Other agents may of course-be employed in the oil compositions, such agents including dyes, pour point depressants, sludge dispersers, thickeners, viscosity index improvers, oiliness agents, and the like. In addition to being employed in lubricants, the additives of the present invention may also be used in other mineral oil products such as motor fuels, heating oils, hydraulic fluids, cutting oils, turbine oils, transformer oils, gear lubricants, greases and other products containing mineral oils as ingredients.

What is claimed is:

1. A hydrocarbon product having incorporated therein in the range of about 0.01 to 20% by weight of an organo-tetravalent tin compound of the formula (RUSH SI(LN/ R wherein w is 2 to 3, y is 1 to 2, w plus y totals 4, and R and R represent hydrocarbon radicals having 1 to 20 carbon atoms.

2. A composition as in claim 1 wherein said hydrocarbon product is a mineral lubricating oil.

3. A composition as in claim 1 in which said R groups are alkyl radicals.

4. A composition as in claim 1 wherein R is an alkyl radical.

5. A lubricating oil composition comprising a major proportion of a mineral lubricating oil and in the range of 0.1 to 2 by weight, based on the total composition, of dilauryltindi(dibutyldithiocarbamate).

6. A lubricating oil composition comprising a major proportion of a mineral lubricating oil and in the range of 0.1 to 2% by weight based on the total composition, of dibutyltindi(diamyldithiocarbamate).

7. A concentrate consisting essentially of a mineral lubricating oil and the tin compound of claim 1, said compound being present in an amount equal to about 20 to 50% by weight of said concentrate.

8. As a new composition of matter an organo-tetravalent tin compound of the formula wherein R is a hydrocarbon radical having 1 to 20 carbon atoms, w is 2 to 3, X is a reactive halogen, y is 1 to 2, and w plus y is 4, with a salt of the formula wherein Y is a cation selected from the group consisting of alkali metals, alkaline earth metals, and ammonium radicals and R is a hydrocarbon radical having 1 to 20 carbon atoms, suflicient of said sulfur-containing compound being used to substantially completely replace halogen in said tin halide, and removing halide reaction products therefrom.

14. The process according to claim 13 wherein said reaction is carried out in the presence of a substantially inert solvent.

15. The process according to claim 13 wherein Y is an alkali metal.

16. The process according to claim 13 wherein said compounds are heated together at a temperature in the range of about 10 to C.

17. As a new composition of matter an organo tetravalent tin compound of the formula wherein w is 2 to 3, y is 1 to 2, w plus y totals 4, and R and R represent alkyl radicals having 1 to 20 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS 2,641,588 Leistner et a1. June 9, 1953 2,641,596 Leistner et al June 9, 1953 2,648,650 Weinberg Aug. 11, 1953 OTHER REFERENCES Gillman: Report on Organo-Tin Compounds, OSRD, No. 548, Serial No. 236, date May 2, 1942, page 12. 

1. A HYDROCARBON PRODUCT HAVING INCORPORATED THEREIN IN THE RANGE OF ABOUT 0.01 TO 20% BY WEIGHT OF AN ORGANO-TETRAVALENT TIN COMPOUND OF THE FORMULA 